Electrical plug and socket



Nov. 1, 1938. M, ALDEN 2,135,267

ELECTRICAL PLUG AND SOCKET Filed Feb. 25, 1936 2mm; Alder INVENTOR ORNEY Patented Nov. 1, 1938 v UNITED STATES PATENT OFFICE ELECTRICAL PLUG AND SOCKET Milton Alden, Brockton, Mass. 7

Application February 25, 1936, Serial No. 65,581

Claims. (01. 173-332) This invention relates to connecting plugs or Another object of this invention is to provide tube bases and sockets used in connection therea plug or base which, when used with the special with but is also applicable to plug and socket socket of this invention, will allow the inclusion combinations as used for other purposes. of at least ten circuits in an area not exceeding More particularly this invention relates to such that required for the present eight circuits, and plugs and sockets as necessarily include a large yet will furnish a degree of spacing and insulanumber of electrically discrete circuits carried in tion at least equal to that of the present octal a structure of comparatively small physical diplug and socket. mensions. A still further object of this invention is to In the art of electron tube bases and sockets provide a plug member of the type above de- 10 therefor, it has been found necessary with the scribed, into which insulated wires may be fasadvent of such electron tubes having a great tened and which will cooperate with the insulanumber of elements therein, to provide a tube tion upon such wires so as to afford an extremely base and socket which could afiord connection high degree of insulation within the' interior of to the large number of elements in such tubes. such plug. 1.; Owing to space limitations, especially in connec- Yet another object of my invention is to protion with modern radio receiving sets, great diflivi an el al c ec in pl g having culty has been found in affording a connection vision for reducing opportunities for accidental for more than eight circ it with such plug and short circuits or electrical leakage occurring in socket type of connections. If an attempt is he interior thereof. m de to supply more than eight prongs in a Another object of my invention is to provide circle of the largest radius which it is practicable 'a plug member which may be inserted into an to employ for such structures, there is encoun- Octal base of the conventional typ into the tered great difiiculty in making the prongs and improved base constructed according to my in"- sockets therefor sufliciently large to have the re-- Vehtieh Without the p s y of the prongs 0f 'quired mechanical rigidity and strength, and at; such plug entering into apertures of the socket the same time to allow suflicient distance between Other than e particular aperture into Which such individual prongs and sockets as will afford each individual P g is designed t enteradequate insulation for the comparatively high A further Object o t invention is to p voltages whi h are often employed in modern vide a plug and socket combination in which the radio receivers. individual members may readily be brought into It has been found, for example, that even ith conjunction with one another without the necesthe so-called octal type of tube base and socket, y of a high degree 0f v s y of the Various difiiculty is very frequently experienced, which p r ri the p i n f r in m in takes the form of a flash-over or short circuiting ju t on. discharge between adjacent individual prongs, Referring DOW t0 e drawing 1 have illuswhich carry a large difierence of potential therey l embodiments of y ve o between. Even if such a short circuit does not Fig.1 shows in perspective a tube base 0 P u occur, yet the leakage path is so very short that as Commonly Constructed at Present detrimental leakage often occurs, especially under 2 is a Pl View Of an Octal pe socket 40 conditions of high humidity or upon the collece as m y empl y at pr tion of dust or dirt between the prongs or the 3 is 911319111 View O t bott of a base sockets. or plug embodying. my invention,

This invention has as one object the provision 4 is n elevation partly in i n f th of a tube base or plug member which will be structure of F 3, taken upon t e l e 4-4. physically stronger, easier to manufacture and 5 is a D1811 V O a ket structed cheaper to construct than the present type of according to y ihventienoctal tube base. W Referring now to Fig. 1, there is shown a body Another object of this invention isto provide portion I l of suitable insulating at al, nto s ch a tube base or plug which may be em lo d which are fastened a series of projecting metallic 5 with sockets of the type now in use. In other pins l2, l2 extending at right angles to the plane words, the tube base of this invention will allow f body These p are arranged substantubes or plugs equipped therewith to be inserted tially equi-distant from one another so as to in sockets which may already exist in places such occupy points on the circumference of a circle as radio receivers. whose center will coincide with the center of the to surface of body II. In the center of the surface of body II is located projecting insulating member or boss 13 provided at one point of its periphery with a projecting fin I4. Boss 13 is made somewhat longer than pins I2 so that it will come in contact with the surface of the socket into which the plug is to be inserted before pins 12 can enter such socket.

Referring now additionally to Fig. 2, there is shown a'body member 2| provided with suitable fastening ears 22, 22 having therein apertures 23, 23 to allow the socket as a whole to be screwed or otherwise fastened on to a suitable panelor other support. Body member 2| is provided with an annular groove 24, in which are located a series of apertures 25, 25 designed to receive plug pins v42. Located closer to the center than groove 24 is another annular portion 26 whose surface may be substantially upon the same plane as the outer surface 21 of body 2|. Annular portion 26 is provided at one point with a radially extending depression 28 cut out of the insulating material and the center 29 of the socket is also out out so as to afford entry therein for boss [3, whose fin I4 registers with the portion 28, so as to allow boss l3 to enter cut-away portion 29 only when a certain angular relationship exists between the plug and the socket.

When the structure of Fig. 1 is produced on a commercial scale, there are encountered certain difficulties, especially in connection with the formation of the boss l3 and fin I4. The common method of producing such structures economically and uniformly, is to mold them from a suitable plastic insulating material, and it is to be understood that where I have referred in this specification to certain portions being cut out of the insulating material, that such cut away portions may equally well be formed by the use of a suitable mold.

When the molding of a structure such as that shown in Fig; 1 is attempted while maintaining all the parts constructed of insulating material as solid bodies, great difilculty is experienced with the boss I3, which will not cure, or reach a properly hardened condition in the same length oftime as the comparatively thin base portion of the structure. Consequently it has been found desirable to construct boss l3 in a hollowed-out fashion, in order to ensure that it cure in approximately the same time as the rest of the structure and likewise in order to ensure that the insulating material used for molding will completely enter the mold, so that the outer surface of member l3 will be properly formed.

While the above method of making a plug such as that of Fig. 1 has been more :or less successfully employed, yet certain difliculties have been experienced with the completed structure. When boss I3 is made hollow, it lacks a strength commensurate with the wear and stress to which it is subjected while inserting the plug into a socket. Such structural weakness frequently leads to the breaking oif of this boss, and when the boss has broken off, the complete plug structure becomes practically useless since it may be inserted with the prongs registering at random with the holes in the socket. If the plug structure forms the base of an electronic tube, this disadvantage becomes increasingly important, since such a breaking off of boss l3 will then result in the effective loss of an electronic tube whose value is many fold that of the plug portion thereof.

If anattempt be made to use such a tube, whose plug portion has lost its property of properly locating the prongs with respect to the socket, the chances are that the tube prongs will make contact with the wrong electrical circuits. If such a wrong connection is made, not only may -it permanently damage the tube itself, but liketo be hereinafter described.

The body 3| -of my plug may conveniently be made of molded material as in the caseof Fig. 1. A series of prongs 32, 32 are mounted upon the circumference of a circle around the center of this plug in a fashion similar to the prongs l2 shown in Fig. 1. These prongs are .of such size and location as to correspond with the openings 25 as shown in the tube socket of Fig. 2, and may be connected either to electrical conductors or to the elements of an electronic tube according to whether this structure is to be used as a connecting plug or as a tube base.

It will be noted that the center of the circle constituted by prongs 32, does not contain a bosslike member, but in its stead are located two additional prongs 33 and 34, the latter prong being made considerably the larger in size. Prong 33 mayconveniently be made of the same size as prongs 32. .As will be more clearly apparent by reference to Fig. 4, prong 34 is not only larger in diameter but also has a greater length than the prongs 32 or 33.

The plug of Fig. 3 is adapted to enter the socket of Fig. 2 in the same general fashion in which the plug of Fig. 1 enters this socket. The longer prong 34 cannot enter any of the apertures 25, since its diameter is too large to permit this. Likewise unless all the prongs 32 are located in a position corresponding to the annular depression 24, prong 33 will rest upon some solid portion of the socket and will prevent the prongs 32 from entering apertures 25. When an attempt is made to insert the plug of Fig. 3 into the socket of Fig. 2, it will be found that the first step necessary is to allow prong 34 to enter the large central opening 29. If the plug is then moved about, it will be found that some one or more of the prongs will keep the plug from entering the socket sufficiently to allow any contact between prongs 32 and the socket contacts which are located in apertures 25. Such difliculty will be encountered until the plug has been so moved about that prong 33 lies within the radial depression 23. When this latter event occurs, it will be found that both prongs 34 and 33 will enter central aperture 29, and at the same time prongs 32 will enter their proper and respective apertures 25."

The advantages of the plug structure just described over the type of plug shown in Fig. 1, as far as its use in the conventional type of octal socket shown in Fig. 2 is concerned, are that the mechanically weak boss 13 and fin l4 which increase the difficulty and cost of manufacture of the plug, have been replaced by metallic prongs which may be molded in the body portion of the plug in exactly the same fashion that prongs 32 are molded therein. Thus the ability of the plu to withstand mechanical strain and wear has been greatly increased, with a consequent effective to prongs 32, but also to the more centrally located prongs 33 and 34, and the use of such additional prongs as contact making members will be hereinafter described.

The body portion 3| of the plug is shown withlateral walls and with a hollow interior portion 52.' The inner surface of walls 5| may conveniently be threaded as indicated at 53 in order to allow a cap or other suitable closure member to be screwed therein, but it is to be understood that any other method of closure is possible, or that the plug may be left open at the top if so desired.

Prongs 34 and 33 are shown in section, illustrating the hollow passages 54. and 55 respectively which extend longitudinally of these prongs. The bottom of interior chamber 52 is tapered away from the upper end of each prong, as indicated at 56, 56. Several insulated conductors 51 are shown. entering the prongs. Such conductors may consist of an outer insulating sheath 58, and an internal metallic conductor 59. The outer sheath 58 may be of a nature which will allow it to slide to a limited extent along the core 59. Such a conductor is shown inserted in place within prong 33. The metallic core 59 may occupy.

substantially the entire length of the prong and may conveniently be attached thereto by a drop of solder (not shown), inserted at the point indicated by reference numeral 55. When such a conductor is inserted in prong 33, the insulating sheath 58 may be pushed back to a limited degree and then the inherent elasticity of such sheath will tend to force it into the enlarged opening formed in body 3| by the space between the tapered portions 56, 56. This brings about a close insulating union between the insulatin sheath of the conductor and the insulating material of which body 3! is composed, as indicated at the point 60. In case that insulating sheath 58 is not of a nature such that it will slide alon core 59, a portion of the insulating sheath may be removed and the conductor inserted in prong 33 until sheath 58 is in close engagement with tapered portions 56, and thereby substantially the same results as just pointed out may be secured.

It may be seen that the close engagement of the conductors with the body portion of my plug, as far as insulating portions are concerned, will minimize the current leakage and possibility of flash-overs, which difliculties have been herein before described.

Referring now to Fig. 5, I have here illustrated.

a type of socket, especially suited for use with the form of plug shown in Figs. 3 and 4. This socket comprises an insulating body 4|, provided with ears 42. These ears may conveniently be provided with apertures 43 in order that the V socket may be secured to a panel or other suitable mounting. An annular depression 44 is provided with apertures 45, .within which apertures may be located the socket contacts (not shown) for engaging the plug prongs entering such apertures. Within annular depression 44 is located a portion of the socket whose surface lies on substantially the same plane as the outer portion 41 of the socket. This portion 46 is provided with two apertures 48 and 49, of which aperture 49 may conveniently be the same size as apertures 45, while aperture 48 may be made considerably larger in diameter. Apertures 48 and 49 may likewise be provided with internal contacts (not shown) which enable them to afford electrical contact with plug prongs entering therein.

It can be seen that the plug structure shown in Figs. 3 and 4 will readily enter the socket shown in Fig. 5, the large prong 34 entering the large aperture 48 and the small prong 33 entering the aperture 49.

The entry of these two particular prongs, not only will cause the other prongs 32 to register with their respective correct apertures 45, but also will afford two additional circuit connections, by virtue of prongs 3| and 34 functioning as additional connecting prongs. Thus it can be seen that I have devised a plug which will afford a means of circuit connection for any number of circuits up to ten, without an increase in size over the usual plug employed in connection with octal sockets and also without reducing the factor of safety of insulation between such circuits. Likewise this same structure functions to afford up to eight circuit connections with already existing sockets of the type shown in Fig. 2.

The many practical uses of such a combination plug structure will be apparent to those skilled in the art. For example it is frequently desired to insert an attachment plug in' a tube socket, in lieu of the tube base itself in order that all the circuits entering such socket may be brought out to an external measuring or indicating device such as a radio set analyzer. Likewise it is desirable for a plug and socket combination to carry more than eight circuitaespecially in such cases as remote control devices which may be plugged into a set. It can be seen that by the use of the plug of this invention, a set analyzer or other measuring device may be plugged not only into already existing tube sockets having eight circuit connections, but also may be plugged into such sockets as are constructed according to the design of Fig. 5, where ten connections must be obtained.

With the development of the art, the number of element connections necessary for an electronic tube has been continually increasing and therefore when further advance in the art may render necessary the connection to nine or ten tube elements, the adoption of a socket in accordance with the form disclosed in Fig. 5 and the adoption of a tube base in accordance with the design of plug shown in Figs. 3 and 4, will afi'ord a ready means of securing this result.

Other uses and advantages of my invention will be apparent to thoseskilled in the art- I claim:

1. In combination, a socket and plug, the socket having a plurality of prong openings arranged substantially in circular formation and also having two prong openings within said circular formation, one of said last mentioned prong openings being materially larger than the other'prong openings, both said last openings lying away from the center of said circular formation, said socket being provided with a surface groove within which said circular formation of prong openings lies, and said plug having pins correspondent in relative position with said socket openings, whereby registration of the circularly arranged pins with said groove and registration of only one pin lying within said circular formation with the corresponding opening will determine registration ofall the remaining pins with their correspondent openings.

2. A combination including a socket provided with a large'central opening and a guiding dethereabout, and including a plug having pins circularly arranged to correspond to said circularly arranged socket openings, and also having within said circle of pins a rigid guiding structure, including a pair of spaced members each disposed eccentric with respect to the plug, the maximum width of said guiding-structure being greater than the diameter of the circular portion of the key hole shaped opening and less than the maximum width of the key hole shaped opening, whereby said guiding structure can enter said keyhole opening only when a given angular relationship of plug and socket is provided, so that at least part of said guiding structure will at least partly enter the grooved portion of said keyhole opening.

4. A device according to claim 3 in which at least a portion of said guiding structure is provided with metallic edges.

5. A connector plug and socket combination, including a plug provided with a plurality of projecting contact pins at least one of which is longer and larger than the other pins, said longer pin and at least one other pin being disposed eccentric with respect to said plug and including a socket having at least one larger opening so shaped and located that said larger pin is capable of entry therewithin, said socket also having other and smaller openings into which said other smaller pins are capable of entry, some of said other pins lying in a circle and at least the majority of said other smaller openings lying in a circle, and said socket being provided with a surface groove embracing therein the entrances to said circularly arranged openings, whereby said longer pin will necessarily enter said larger opening before any one of the other pins can enter its respective opening when engagement of said plugand said socket is performed, and whereby registration of said larger pin with said larger opening and of said circularly arranged pins with said groove willsimultaneously determine the registration of all other pins and their respective openings only when there exists a predetermined relationship of angular rotation between said plug and said socket.

MILTON ALDEN. 

